The present invention relates in general to audio amplifiers and, in particular, to an amplifier calibration apparatus and method for calibrating the gain of an amplifier automatically, such that upon manual control of the gain thereof the usable range is consistent from power-up to power-up and is independent of component aging.
There are numerous methods for amplifying audio signals. The most prevalent of which is the use of operational amplifiers. Operational amplifiers provide good linearity in their respective range and good noise and impedance characteristics, all of which is particularly useful in high-end audio components.
Another approach to amplifying audio signals involves the use of a potentiometer in conjunction with an operational amplifier to alter the resistance of the audio path so as to control the gain over that path. Although potentiometers are significantly less expensive than operational amplifiers, they are rarely used in the critical path of high performance audio equipment. Potentiometers suffer from unacceptably large variations in resistance, which prevent the balancing of two channels in a stereo system and further prevents the maintenance of a range through which a user can consistently control volume.
It is thus an object of the present invention to provide an automatic amplifier calibration apparatus which allows the use of potentiometers, while substantially negating variations in resistance, thus providing calibration for each individual channel and desirable balance between those channels.
It is a further object of the present invention to provide an amplifier calibration apparatus which may be added into an existing audio system designed to accept such an apparatus as an add-on board.
These and other objects of the present invention will become apparent in light of the present specification, claims and drawings.